The RockBox Blue is interesting in that it seems to combine many of the functions that have appeared in some of the advanced apps (e.g. iRegatta) with dedicated hardware and a screen that you can read in bright sunlight.
It also is one of the only hardware units that works in both portrait and landscape mode and comes with a remote control so that you can change the display from a distance.
Functions include, trend arrows for speed/VMG,COG, Starline distance, Countdown, Knock-lift indicator, Speed/VMG charts, Waypoints, Data logging
However all this functionality comes at a cost – around $700.00 for the unit and a further $100 for the remote.